Ascertain the role of metabolism in the induction of rat mammary tumors by certain polycyclic aromatic hydrocarbons (PAH) and to determine whether alternation in the disposition, metabolism, binding, and dna repair are related to the differences in susceptibility of certain strains, ages, and altered hormonal conditions. These objectives will be pursued through investigation of the distribution of the carcinogens at various levels in the host, their biotransformation, and their interaction with tissue macromolecules.